Some People Believe Running an Electric Fan in a Closed Room Can Kill You

February 10, 2012 at 2:00 am 10 comments

By Chad Upton | Editor

In South Korea, it is a commonly held belief that an electric fan can cause death if it is blowing on you overnight in a closed room.

To prevent “fan death”, the Korean government’s Consumer Protection Board urges everyone to leave a door or window open and use the oscillate function or a timer that automatically shuts the fan off. They also list fan death as one of the top five fatal summer accidents.

The exact origin of this phenomenon is not known for sure, although it allegedly emerged in the 1970s. Some people believe the Korean government may have created this ideology in an effort to save energy during the energy crisis. Oh, and fan death is not limited to just fans, it also includes air conditioners.

South Korean media outlets credit fans and air conditioners for deaths too. In fact, between 2003 and 2005, some 20 deaths were reported to Korea’s Consumer Injury Surveillance System.

Many experts in South Korea firmly believe in fan death, including respected doctors and scientists. South Koreans don’t always agree on why fans can cause death but the following theories are often cited.

Hypothermia is a common one. It’s true that if your body temperature drops low enough, you can die. However, experts claim your body temperature needs to drop by about 16°F (10°C) for this to happen. Since fans don’t actually cool the air, it is not plausible that a fan could cause this temperature drop by convection cooling alone. Not to mention, people frequently asleep outside in much cooler temperatures and survive without question.

That leads to the asphyxiation theory — the belief that somehow these fans reduce the available oxygen in the room. There is no scientific proof to suggest this is true. In North America, the believe is almost the opposite since fans are often recommended to help babies sleep (as a source of white noise).

Another theory is that fan deaths are actually suicides, but reported as fan deaths in the media to spare the family from any cultural shame associated with suicide.

A fourth theory is that the fan combined with hot air creates a convection oven like effect, raising a person’s body temperature, causing them to sweat until they are dehydrated. This theory is interesting because it’s kind of the opposite of the first theory and it could theoretically work, but not likely in South Korea. You see, the highest average temperature in South Korea is about 84°F (29°C), which is still well below body temperature and well below the temperature where the body will start to shut down and die (around 107°F / 42°C). The highest officially recorded temperature in South Korea is 104°F (40°C), just slightly above core body temperature.

The same way a fan doesn’t cool air, it also doesn’t heat it, it just speeds up the transfer of heat between the air temperature and your body. That is why you can cook something in a convection oven at a lower temperature — the fan doesn’t make it hotter, it just improves the transfer of heat. In a traditional oven you need to use a higher temperature setting to make up for the fact that still air doesn’t transfer heat nearly as well.

During extremely hot weather, heat can cause fatalities. Because fans can increase the rate at which your body temperature increases, the EPA does caution against using a fan at temperatures above 90°F (32°C). Don’t mistake this as a suggestion that fans can kill you — you are at risk of dying in extreme heat whether you use a fan or not. In terms of Korean fan death, the 90°F warning is still 6° higher than the average high temperature in South Korea.

It is interesting that this theory is so prevalent in just one country. Most people outside of South Korea do not believe in fan death and there does not seem to be any scientific evidence that a fan will kill you while you sleep.

Do you believe it? Let us know in the comments.

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Sources: wikipedia (Fan Death), snopes, ask a korean,,,,

Photo: db0yd13 (cc)

Entry filed under: Demystified, History and Origins. Tags: , , , , , , .

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10 Comments Add your own

  • 1. mike  |  February 10, 2012 at 5:22 am

    Thanks for pointing this out. My parents are full believers of the idea, and I remember hearing it often while growing up, but never had an answer for it myself.

  • 2. David S. McQueen  |  February 10, 2012 at 7:17 am

    It’s an “old wives tale” that’s passed down through generations of Koreans. In Viet Nam, many believe that the geography (the terrain) of the location where a person was born determines his future. I even read a book that was illustrated with terrain maps. The Vietnamese man who was explaining this “scientific” fact truly believed his destiny was based on the terrain of his birth.

  • 3. Teresa  |  February 10, 2012 at 9:08 am

    I have slept with a fan going in my bedroom every night for years. Many times with the door closed as well as all of the windows. I have never even felt close to suffocated, freezing, or overheating. This sounds highly suspicious to me!

  • 4. Denisa  |  February 13, 2012 at 8:01 am

    In Romania, we have a fear of the air draft. So we travel with the train’s or car’s windows closed most of the time, because if we catch a draft, we will get a cold or even worse, toothache.
    Even some doctors say, when we have headaches or bad toothaches, that they may have been caused by a cold air draft.
    It’s a national paranoia! :))

    • 5. chriscp  |  September 24, 2013 at 9:19 am

      There are people in the U.S. who also believe that a draft can make you sick. Or that “going outside with a wet head” will cause you to catch a cold. But the common cold is caused by a virus, not the outside (or inside) temperature. Strangely enough some of the same people who believe that a draft can give you a cold live in homes with air conditioners of one kind or another.

      There’s still a lot of people who follow old wives’ tales and superstitions.

  • 6. Nordicskiwidow  |  February 15, 2012 at 7:26 am

    Here’s an extract from a blog entitled ‘Ask a Korean’:

    Don’t believe the Korean? Would you believe the U.S. Environmental Protection Agency? This pamphlet from the EPA, at pages 49 and 51, clearly states the hazard of using portable electric fans during high heat. It specifically says “Portable electric fans can … increase the circulation of hot air, which increases thermal stress and health risks[,]” and “DON’T use a portable electric fan in a closed room without windows or doors open to the outside.”

    Or how about a climatology professor who works for the National Weather Service? In an interview with NPR about extreme heat warning system, Dr. Kalkstein specifically mentions the danger of fans in a hot, enclosed room (At 13:45 mark): “One piece of advice we tell them not to do is to sit in front of a fan in a hot apartment because it has a convection effect.”

    So you can see, as you actually stated yourself with the convection example, there is a scientific basis for the belief, however rare an occurrence it actually is. Obviously, in South Korea, they have got a bit carried away with it.

  • 7. alaampanah  |  June 21, 2012 at 2:13 pm

    the culprit is the electric motor in the fan. The electric motor uses brushes which causes sparks. This process converts the oxygen molecules 02 into ozone molecules 03. Ozone is not good for our health and other organic material. For example if a rubber tyre is kept for a long time near an electric motor, it will be damaged. But the fan has a small motor so the amount if ozone is less significant. May be damage to health may occur after long period.

    The Canadian Center for Occupation Safety and Health reports that:

    “Even very low concentrations of ozone can be harmful to the upper respiratory tract and the lungs. The severity of injury depends on both by the concentration of ozone and the duration of exposure. Severe and permanent lung injury or death could result from even a very short-term exposure to relatively low concentrations.”

    • 8. ps3cows  |  February 25, 2013 at 9:35 pm

      Household power uses alternating current (AC). I’m pretty sure only direct current (DC) motors use brushes.

      If your fan is sparking, throw it away.

      • 9. D.W. Read  |  August 3, 2013 at 10:51 pm

        Not so. I have a sewing machine and a power woodworking tool that use brushes and run on household current.

      • 10. Common Sense  |  January 29, 2014 at 5:36 am

        You do realize that many common household things use DC, right? Ever see a plug coming out of a large box at the end of a power cord? It’s a device which changes AC to DC.

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